Buying in bulk at Costco can save your family lots of money—depending on what you buy. To find out exactly which items are the best deals at the wholesale club, personal finance blog Squawkfox did a shopping experiment comparing unit prices on fresh, frozen, and packaged goods between a local grocery and Costco.

The results are interesting, with the local grocery store coming out ahead for fresh foods (fruits, cheese, chicken, and milk), but Costco saving almost 21% on everything else priced out:

Importantly, the quality of the frozen foods at Costco was better than the supermarket's generic brand.

In short, a Costco membership might make sense for buying in bulk once a month for those strategic items (frozen foods, canned goods, diapers, etc.)—keeping in mind our previously tip to avoid buying soda, toilet paper, and office supplies at Costco because you can get these at the supermarket on sale cheaper with coupons. Of course, your mileage may vary, so definitely check prices yourself, but the figures above may give you an idea if shopping Costco for certain foods is worth it or not for you. Check out the full article for more tips on making the most of a Costco membership and saving more at Costco.